ASTM F2503 Standard: Marking and Labeling for the Safety of Medical Devices in the MR Environment

Why is ASTM F2503 Essential?

An implant, infusion pump, patient monitor, or any other device introduced into the MR environment may create hazards. Interactions with the MRI static magnetic field, gradient fields, or radiofrequency (RF) fields can lead to:

magnetic effects, such as displacement force or torque;
electrical effects, potentially causing electronic malfunction or unintended stimulation;
vibrations induced by gradient fields;
heating of the device or surrounding tissues resulting from radiofrequency and/or gradient field exposure;
degradation of medical device performance or MRI image quality.

In certain situations, these effects may present a risk to the patient, user, or healthcare personnel.

To address these challenges, ASTM F2503 establishes a common language based on standardized symbols and harmonized labeling. It enables medical device manufacturers, healthcare facilities, and regulatory authorities to rapidly identify the conditions under which a medical device may be used in the MR environment.

What is ASTM F2503?

ASTM F2503, entitled “Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment” defines marking and labeling requirements for equipment that may enter the MR environment. It is the internationally recognized reference standard for communicating the conditions of use of a device in the MR environment. In particular, it has received official recognition from the U.S. FDA.

Originally published in 2005, its most recent version is ASTM F2503-26, published in May 2026.

The standard applies to all items that may enter the MR environment, including implants, active medical devices, accessories, and equipment used around MRI systems (stretchers, contrast media injectors, patient monitoring systems, pumps, furniture, accessories, etc.).

The objective of ASTM F2503 is to eliminate ambiguity when communicating a device’s MRI safety status and to provide users with clear and consistent information. In particular, it defines:

Classification into the three categories: MR Safe, MR Conditional, and MR Unsafe;
the associated pictograms (standardized shapes, colors, and typography);
labeling requirements;
readability and accessibility requirements for this information.

ASTM F2503 also reviews the principal effects that may be observed when a medical device is introduced into the MR environment and references several test methods that can be used to evaluate them. However, the standard is not intended to provide an exhaustive list of all potential risks. The phenomena described may not be relevant to every device and, conversely, certain device-specific hazards may not be explicitly addressed by the standard and may require additional evaluation.

It is therefore the manufacturer’s responsibility to perform a risk analysis tailored to the device in order to identify all potential hazards associated with its use in the MR environment and determine the most appropriate test methods to demonstrate that these risks are adequately controlled.

Because the MR environment is highly specific and the underlying interaction mechanisms can be complex, it may be beneficial to rely on MRI safety experts during this critical risk assessment stage. Healtis offers a dedicated MRI Assessment Strategy service that includes hazard identification and selection of the most appropriate test methods.

What Do the MR Safe, MR Conditional, and MR Unsafe Categories Mean?

ASTM F2503 defines three categories: MR Safe, MR Conditional, and MR Unsafe. Each classification is associated with a standardized symbol that allows users to quickly identify the conditions under which a device may be introduced into the MR environment.

MR Safe: No Known MRI-Related Hazards

An MR Safe device presents no known hazards resulting from exposure to the MR environment.

Typically, this classification applies to devices composed exclusively of materials that are:

non-metallic;
non-magnetic;
non-electrically conductive.

Examples :

Gowns without metallic components;
Plastic splints or orthoses containing no metallic parts;
Certain silicone catheters;
Patient positioning accessories (pads, cushions, supports) manufactured exclusively from foams or polymeric materials.

A medical device cannot be classified as MR Safe solely because it is made of non-magnetic materials. Some weakly magnetic, or even amagnetic, materials may be good electrical conductors capable of causing heating or other interactions with MRI electromagnetic fields. For this reason, many medical devices are classified as MR Conditional rather than MR Safe.

MR Conditional: Specific Conditions Must Be Met

The MR Conditional category is currently the most common classification for medical devices. It indicates that the manufacturer has established specific conditions of use under which the device has been demonstrated not to pose any known hazards in the MR environment.

The conditions associated with an MR Conditional classification must be made available to users in a clear and unambiguous manner. They are generally provided in the IFU, instructions for use, patient cards, or other appropriate labeling materials.

These conditions may include:

requirements relating to the device itself (operating mode, configuration, accessories used, number or location of implants, device status, etc.);
limitations concerning MRI system characteristics, such as static magnetic field strength or maximum spatial gradient;
restrictions on MRI operating conditions when the device is present, including authorized RF coils, permitted imaging sequences, MRI operating mode (Normal Operating Mode, First Level Controlled Operating Mode, etc.), RF exposure limits (SAR/B1+RMS), gradient exposure limits, or maximum scan duration;
patient or device positioning requirements relative to the MRI isocenter or specific scanner regions;
information regarding expected image artifacts;
special precautions to be observed before, during, or after the MRI examination.

For many years, MR Conditional conditions were presented as free text within device documentation. Presentation in a tabular format is now recommended. Examples of such formats are provided within the standard.

MR Unsafe: Unacceptable Hazard in the MR Environment

An MR Unsafe device presents an unacceptable hazard in the MR environment. Consequently, it must never be introduced into the MR environment.

Typical Examples :

Ferromagnetic scissors;
Certain equipment containing strongly magnetic materials;
Devices that may become dangerous projectiles.

Conclusion

ASTM F2503 provides an essential framework for communicating the MRI safety conditions of medical devices. It establishes marking and labeling requirements intended to harmonize practices and facilitate the rapid identification of device use conditions by healthcare professionals.

However, the standard is not intended to serve as a comprehensive methodology for managing the risks associated with introducing devices into the MR environment. The identification of device-specific hazards, the assessment of their relevance, the selection of appropriate testing, and the interpretation of results remain the responsibility of the manufacturer and must be adapted to the device characteristics, intended use, and anticipated MRI exposure scenarios.

In practice, a structured MRI safety assessment approach enables manufacturers to reduce unnecessary testing, anticipate regulatory expectations, and secure their market access strategy. This is the approach adopted by Healtis, supporting medical device manufacturers from MRI-related risk analysis through the definition of MRI safety and compatibility testing, result interpretation, labeling recommendations, and drafting of MRI labeling documentation.

Would you like to gain a better understanding of ASTM F2503 requirements or discuss one of your projects? Feel free to contact us (Contact Form Anchor) to speak with one of our experts.